This invention relates to wood working tools and in particular to tapered plug cutters used to produce wooden plugs.
Wooden plugs are often used to fill round holes in a workpiece to conceal fasteners and screws that have been set below the surface of a workpiece. Generally an overly long wooden plug is applied and glued into the hole to be filled and has its excess trimmed to the surrounding surface height and sanded smooth. Ordinary wooden dowels have been used for this purpose in the past, but as dowels are made with their axis parallel to the grain of the wood and as the end grain of wood accepts stains and finishes differently than the face grain of a piece of wood, it is desirable that plugs be made with their axis at right angle to the grain. When plugs of this type are used, staining and finishing of a workpiece can be achieved with the plugs being almost invisible. Further regarding the staining and finishing of wood, different woods accept stains differently, so it is often desirable that plugs for a workpiece be made from the same wood, or even the same piece of wood, as the workpiece. That being the case, it is desirable that a woodworker have the option of manufacturing their own plugs, and so numerous plug cutters have thus been introduced to provide woodworkers with that option.
There are plug cutters are used to produce cylindrical plugs. However a cylindrical plug may result in a gap or a circle of glue between the workpiece and the plug. Accordingly tapered plug cutters have been developed which produce tapered plugs. Tapered plugs are more likely to fit snugly into their holes, to limit the gap around and to provide a good appearance.
Some woodworkers have noticed that while tapered plugs improve the fit in holes, they also have the tendency to tip sideways during insertion and so compromise their placement in a workpiece. To limit the amount of movement that occurs when a plug is inserted, some woodworkers prefer to have both a tapered portion, to maintain the tight fit, and a cylindrical portion, to limit the movement during insertion. The cylindrical portion is at the minor diameter end of the tapered portion of the plug. By having the cylindrical portion at the minor diameter end, the cylindrical portion limits the amount of movement the plug can experience when inserted and so keeps the plug correctly oriented. Preferably the cylindrical portion of the plug is of a diameter the same as or very slightly less than the hole to be filled, to gain the greatest movement limiting effect while still fitting in the hole.
The cutting characteristics of plug cutters depends on the geometry of the cutting edges of the cutter. It is common to find plug cutters that have a plurality of cutting edges that extend generally radially from the axis of the cutter. This arrangement yields edges that cut the wood with a scrapping action. Alternatively, the cutting edges can be tilted backward from the direction of rotation so as to provide some positive rake to the edge, and so improve the cutting characteristics of the cutter.
During the operation of a plug cutter, it is recommended that the work be conducted in a drill press, as opposed to a hand held drill, as the forces on the cutter tend to cause considerable wandering tendencies. This wandering tendency is greatest while starting to cut a plug and decreases when the cutter has moved into the stock, but is substantial enough that use of the cutter in a hand held drill is difficult. The larger the diameter of the formed plug, the more pronounced the wandering tendencies and so the more difficult and dangerous the exercise becomes. The use of a drilling guide, to align and steady the cutter, can make hand forming of plugs possible, but the process is slowed down as the guide has to be clamped to the stock and moved for each plug that is formed.
Once the plug has been formed in the stock, it is detached either by prying and snapping it from the stock, for example with a screwdriver, or by cutting it from the stock with a saw, by cutting across the lower portion of the plug.
Several plug cutters have been developed to manufacture tapered plugs with cylindrical portions. U.S. Pat. No. 5,213,456 issued to Lee on May 25, 1993 shows a cutter that will form a tapered plug having a cylindrical portion at the minor diameter end of the tapered portion. Similarly, U.S. Pat. No. 5,401,125 issued to Sevack et al. on Mar. 28, 1995 shows a cutter that forms plugs having a cylindrical portion at the minor diameter end of a generally flared body portion, the flared body portion providing improved fit and alignment during insertion over cylindrical and tapered plug performance. Additionally, the Sevack cutter shows a hole through the shank that may be used to eject plugs that have sheared off from the stock during forming of the plug, allowing for improved removal of sheared plugs. U.S. Pat. No. 5,810,524 issued to Wirth et al. on Sep. 22, 1998 shows a cutter that has clearance applied to the inner surfaces of its cutting edges to minimize the contact between the cutter and the plug.
Despite these and many other improvements to plug cutters there still remain deficiencies and it is the ambition of this invention to overcome these deficiencies. In particular it would be advantageous to have a plug cutter that forms tapered plugs, having a cylindrical portion, that has good cutting characteristics, increased clearance between the cutter and the formed plug and increased ease of removing a sheared plug from the cutter.
The present invention is a plug cutter for use in association with a drill, drill press and the like and is for producing a plug. The plug cutter includes a shank, a body portion, an outside cutter and an inside cutter. The shank has a longitudinal axis and is adapted to engage the drill. The body portion is integrally attached to the shank and extends downwardly therefrom. The outside cutter extends downwardly from the body portion and the inside cutter extends downwardly from the body portion and is spaced from the outside cutter. The outside cutter may have an outside cutting edge with a positive rake. The inside cutter may have an inside cutting edge with a positive rake.
In another aspect of the invention a plug cutter is for use in association with a drill, drill press and the like and is for producing a plug. The plug cutter includes a shank, a body portion, a plurality of blades and a shoulder. The shank has a longitudinal axis and is adapted to engage the drill. The body portion is integrally attached to the shank and extends downwardly therefrom. The plurality of cutting blades extend downwardly from the body portion and are adapted to cut a plug. The shoulder extends outwardly from the body portion and is adapted to limit movement of the plug cutter into a workpiece.
In a further aspect of the invention a plug cutter is for use in association with a drill, drill press and the like and is for producing a plug. The plug cutter includes a shank, a body portion, a plurality of blades and a cavity. The shank has a longitudinal axis and is adapted to engage the drill. The body portion is integrally attached to the shank and extends downwardly therefrom. The plurality of cutting blades extend downwardly from the body portion and are adapted to cut a plug. The cavity is formed in the body portion to provide access to a top of a plug.
Further features of the invention will be described or will become apparent in the course of the following detailed description.